Please follow these steps:
1) Request a password reset for the email address associated with your Facebook account here: https://chordify.net/user/password
2) Follow the instructions to reset the password, and then you can log in without the 'Continue with Facebook' option on Chordify, using the email address and newly created password
If you have any questions about this or need any assistance, please get in touch at: support@chordify.net.